High-Temp Silicone for PVC seal venting Propane water heater

[Jim]

Our propane water heater vents through a 3" PVC pipe on top of the unit. It look as though a bead of silicone(???) was placed around the area where the PVC piping connects to the vent line from the heater itself (it was installed about 6 years ago). I have noticed that this seal has sprung a very small leak and when venting, some of the air is blowing into the surrounding area. Obviously, I would like to reseal this connection.

Is a special purpose silicone used for this seal? The instruction manual says to use a high-temperature silicone for the seal, but no local stores seem to have heard about this type of silicone.

Is the high temperature necessary due to the heat from the venting itself?

THANKS

[Joseph Meehan]

It the auto parts store, you should find it there.

[Tom J]

Go to the auto parts store and get a tube of high temp silicone gasket maker. May be blue in color but works fine. You can pay more and get duct joint silicone at a plumbing supply company.

Tom J

[Joe Bobst]

The service temperature upper limits for both common silicone sealants and high temperature sealants is well above the softening point of PVC, so IMO it seems to be a case of overkill to recommend the high temp variety. Most high temp formulations are red. If your sealnnt is some other shade or cleas it may be the conventional variety. HTH

Joe